Stimulated emission at silicon bandgap energy from a nanostructured silicon PN junction diode

Stimulated emission at silicon bandgap energy has been observed from a silicon nanostructured PN junction diode with a ridge waveguide structure using current injection at room temperature. The output optical power increases superlinearly and multiple spectral peaks appear at wavelengths longer than the main peak of spontaneous emission as the injection current reaches a threshold. A theoretical analysis on population inversion and optical gain at bandgap energy in indirect bandgap semiconductors suggests the possibility of stimulated emission.